1. Field of the Invention
This invention relates to liquid-cooled (so-called cold stored) cylinder sleeves for combustion engines of the reciprocating piston type.
These cylinder sleeves often suffer corrosion on the external surfaces in contact with the cooling liquid, the cavitation processes taking place on the said surfaces being by no means the least important cause thereof. Corrosion of this kind is particularly observable in the zones adjacent to the intersection line between the "piston pivoting plane" passing through the longitudinal axis of the cylinder and the wall of the cylinder sleeve. By "piston pivoting plane" we mean a plane containing the longitudinal axis of the cylinder sleeve disposed at right angles to a plane containing both the longitudinal axis of the cylinder sleeve and the pivoting axis of the piston. These cavitations are caused, at least to a considerable extent, by vibrations of the walls of the cylinder sleeves. As a remedy, therefore, cylinder sleeves have been given comparatively ample wall thicknesses, in order to counteract the harmful vibrations by increased rigidity of the entire cylinder sleeve. In these cases the wall thicknesses often exceed the dimensions which, from the point of view of strength and for the avoidance of vibrations in certain zones of the cylinder sleeve, would have been required to enable the forces acting on the cylinder sleeves to be reliably absorbed. Excessive wall thickness, however, prove disadvantageous, particularly where the dissipation of the heat through the wall of the cylinder sleeve is concerned. For it is precisely from the point of view of good heat transference, of course, that it is desirable to keep the wall thickness to a minimum.
2. Description of the Prior Art
It has already been suggested, in German Specification No. 1,751,296, that a collar provided on the upper edge of the cylinder sleeve and serving to support it should be given varying widths along its periphery. This suggestion, however, is intended as a solution to a problem quite different from that on which the present invention is based. For its purpose is to enable the distance between adjacent cylinders to be kept to a minimum. For this purpose the collars on the cylinders are made narrower at the critical points than on the remainder of their periphery. Care is merely taken to ensure that the total bearing surface of the collar does not fall short of a certain minimum. The sole problem is thus that of making optimum use of the space available in the case of cylinders situated close together. This system, on the other hand, in no way suggests the attempt to which the present invention relates, to influence the dynamic characteristics of the cylinder sleeve by varying wall thicknesses adapted to the force conditions prevailing at different points on the said cylinder sleeve.